Successful treatment of BCCA has resulted from the use of topical Vitamin A Acid, either alone or in combination with liquid nitrogen or tropical 5FU. Other studies include the successful treatment of basal cell carcinoma with topical BCNU, psoriasis with topical CCNU, and ichthyosis with topical alphahydroxy acids, and the unsuccessful treatment of psoriasis with topical Vitamin A Acid. The treatment of a variety of disorders of keratinization with oral 13-cis retinoic acid will begin shortly.